While trying to work with Microsoft Word on a server through .NET the following error was thrown:

Retrieving the COM class factory for component with CLSID {000209FF-0000-0000-C000-000000000046} failed due to the following error: 80070005 Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)).

To resolve this you will need to grant COM permissions to the user running the application pool.

1. Open up Component Services (Start -> Run -> dcomcnfg)
2. Expand Component Services -> Computers
3. Right click My Computer -> Properties
4. On the COM Security tab click Edit Default under the “Launch and Activation Permissions” section
5. Add the IIS_IUSRS group and check allow next to Local Launch and Local Activation